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Re: on-line fossil birds list

This seems to be wrong.  Read Gao and Ren (2006).  It argues
VERY convincingly for a Middle Jurassic age.

Interesting. Please send me the pdf.

I have only read a reply by He et al. (2005) to a critique of their 2004 paper. They defend their conclusion there (but don't mention the Tuchengzi Fm anymore) and show evidence for contamination by older crystals.

Personally, I get the impression that the lateral correlation between almost any two sites is deeply mysterious at the moment. No wonder -- the area is vast and consists entirely of 1000 m high mountains.

"[...] He et
al. (2004) also claim that, contrary to Ren et al. (2002) and
Liu and Jin (2002), ¡°at the Daohugou locality, the fossilbearing
sediments are also found to overlie the Tuchengzi
Formation at a few sites¡±, but they have not cited the
coordinates of the sites where this occurs nor have they
documented this contact in a photograph of these sites."

Well, OK, but that doesn't mean the site doesn't exist...

He H[uai]y[u], Wang X., Zhou Z., Zhu R., Jin F., Wang F., Ding X. & A. Boven (2005): Reply to comment by Liu and Liu on "^40Ar/^39Ar dating of ignimbrite from Inner Mongolia, northeastern China, indicates a post-Middle Jurassic age for the overlying Daohugou Bed", Geophysical Research Letters 32, L12315, 3 pages

There's also a paper by these authors from 2006 on the age of the Dabeigou Fm (Hauterivian-Barremian boundary), but there they don't mention the Daohugou Bed much, IIRC. (The pdf of that one is on the laptop, so I can't check right now.)